Modeling the effect of habitat selection mechanisms on population responses to landscape structure

Abstract

Novel habitats can become ecological traps for mobile animals if individuals consistently select them over habitats with better fitness consequences. Due to challenges with the measurement of habitat selection and quality, ecological traps are difficult to study in the field. Previous modeling approaches have overlooked the importance of selection cues as a key component in the mechanisms giving rise to ecological traps. We created a spatially explicit, individual-based simulation model to evaluate the effects of landscape structure on population dynamics of a hypothetical species under two mechanisms of habitat selection. In habitat-based selection, individuals preferred high-quality patches (leading to adaptive outcomes), selected patches at random (equal-preference) or preferred lower-quality patches (severe ecological traps). In cue-based selection they chose based on a structural attribute that was not directly related to fitness (canopy cover). We applied the model to the case of resident birds in landscapes composed of remnant forests and shade coffee agriculture. We designed simulation experiments with scenarios varying in landscape composition, configuration, search area and criteria for habitat preference. While all factors affected population size and individual fitness, the most important variables were proportion of high-quality habitat in the landscape, criteria for habitat preference and their interaction. The specific arrangement of habitat patches and search area had weaker and sometimes unexpected effects, mainly through increasing outcome variance. There was more variation among scenarios when selection was habitat-based than cue-based, with outcomes of the latter being intermediate between those of adaptive and equal-preference choices. Because the effects of ecological traps could be buffered by increasing the amount of high-quality habitat in the landscape, our results suggest that to truly understand species adaptation to habitat transformation we must always include landscape context in our analyses, and make an effort to find the appropriate scales and cues that organisms use for habitat selection.